Loop taker adjusting mechanism for chainstitch sewing machines



July 21, 1964 H. GROSS 3,141,427

LOOP TAKER ADJUSTING MECHANISM FOR CHAINSTITCH sswme MACHINES Filed June11, 1963 Fig. 4

A 770/? A/E y United States Patent 3,141,427 L00? TAKER ADJUSTINGMECHANISM FER CHAlNlTilTQH SEWING MACHINES Hehnnt Gross, Kaiserslautern,Pfalz, Germany, assignor to G. M. Piafi AG, Kaiserslautern, Plalz,Germany, a corporation of Germany Filed June 11, 1963, Scr. No. 287,146Claims priority, application Germany June 13, 1962 11 flaims. (Cl.1l2200) This invention relates to chainstitch sewing machines comprisinga reciprocatory needle and a thread-carrying hook or loop takercooperating therewith to produce double chain-stitches in a work piecebeing operated on, and more particularly to machines of this typewherein the loop taker, being operated in its normal or operativeposition over a substantially elliptical path in synchronism with theneedle, may be released temporarily and operated to a threading positionfor the easy and expeditious insertion of the loop taker thread prior tothe commencement of a sewing operation.

The known constructions for the operation of the loop taker ofchainstitch sewing machines from the operative position to a morereadily accessible threading position have the disadvantage that theloop taker must be manually returned from the threading. position or itsoperative or retracted position prior to the starting of a sewingoperation. If retraction is omitted due to inadvertence or negligence onthe part of the operator, or as a result of tampering or toying with themachine, the loop taker may collide with the needle or other parts ofthe machine, or the stitch formation may cease, resulting in eitherdamage or breakage of parts or loss of operating time, as well as otherdrawbacks and defects.

In order to prevent starting of the machine with the loop taker in thethreading position, it has furthermore become known to lock the driveshaft of the machine in the threading position of the loop taker by astop pawl and ratchet or the like mechanism. Aside from the re quirementof additional parts and mechanism, this solution still has thedisadvantage that the loop taker must be manually returned to theoperative position before a sewing operation can be started.

Besides, attempts have been made in the past to retract the loop takerto its operative position by spring action. Here again, retraction mustbe released or initiated manually by a control operation ormanipulation.

Accordingly, among the objects of the present invention is the provisionof improved control or adjusting mechanism for the loop taker of adouble chainstitch sewing machine of the type referred toby which theforegoing and related difficulties and defects are substantiallyeliminated; which mechanism will ensure a ready and instant return ofthe loop taker from its threading position to its retracted or operativeposition; which will enable it to dispense with any manual control ormanipulation in returning the loop taker to its operative position afterthreading by automatically retracting the same upon and during thecommencement of a sewing operation; which will preclude any damage tothe machine parts or loss of operating time due to inadvertence ornegligence on the part of the operator; and which mechanism is bothsimple in design and eflicient in operation and may be readilystructurally incorporated in conventional chainstitch sewing machines.

The invention, both as to the foregoing and ancillary objects as well asits novel aspects, will be better understood from the following detaileddescription of a preferred practical embodiment, taken in conjunctionwith the accompanying drawing forming part of this specification and inwhich:

FIG. 1 is a side elevation, shown with portions thereof 3,141,4 2?Patented July 21, 1964 broken away, of a chainstitch sewing machineembodying loop taker adjusting mechanism constructed in accordance withthe principles of the invention;

FIG. 2 is an enlarged perspective view more clearly showing the looptaker operating and adjusting mechanism embodied in FIG. 1;

FIG. 3 is a partial detail view of the stationary cam plate of FIGS. 1and 2 serving to initiate the loop taker retraction upon the starting ofa sewing operation; and

FIG. 4 is a further partial detail view of the cam or locking disk alsoforming part of FIGS. 1 and 2 and serving to efiect final retraction andlocking of the loop taker in its operative position.

Like reference numerals denote like parts in the different views of thedrawing.

With the foregoing objects in view, the invention involves generally theprovision in a chainstitch sewing machine of the type referred to andhaving a reciprocatory needle, a thread-carrying loop taker, a supportor carrier therefor, and drive means to operate the same over asubstantially elliptical operating path in synchronism with said needle,to sew double chainstitches in a Work piece operated on, of operating oradjusting mechanism to operate said loop taker between an operativeposition, for carying out a sewing operation, and a threading position,for the insertion of the loop taker thread prior to the starting of thesewing operation, said mechanism comprising essentially means torotatively support said loop taker by said carrier, and releasablelocking means including first resilient means to normally urge said looptaker to its operative and locked position with said carrier. The looptaker and carrier are connected with one another by second resilientmeans, such as in the form of a coil spring or the like having its endsfixedly engaging the loop taker and carrier, respectively, said secondresilient means being arranged to be stressed or tensioned in the normalor locked position of the loop taker with said carrier. As aconsequence, manual release of said locking means at a predeterminedposition of the loop taker within its operating path, such as bydepression of an operating lever or the like, will result in the looptaker being operated from its (normally inaccessible) or operativeposition a (readily accessible) threading position by the action of saidsecond resilient means.

In order to automatically retract the loop taker to its operativeposition during the starting of a sewing operation there is furtherprovided, in accordance with the present invention, stationary cam meansserving as a stop for the loop taker in the threading position, on theone hand, and being adapted to cam with said loop taker or its supportor carrier upon and during its initial displacement after starting of asewing operation, in such a manner as to rotate the loop taker towardsand to retract it to the operative or locked position with its carrierby the action of the first resilient means.

The releasable loop taker locking means is advantageously comprised of adisk having a peripheral groove and being connected to a loop takersupporting shaft journalled in the loop taker carrier, on the one hand,and a double locking lever fulcrumed upon said carrier and having onearm engaging the periphery of said disk by the action of said firstresilient means which may be in the form of a coil spring connecting thesecond arm of said lever with said carrier. One edge of said groove isadvantageously shaped in the form of a cam or bevelled surface adaptedto cooperate with said first lever arm and being correlated with saidfirst cam means such as to cause said lever at first to approach saidgroove during the initial displacement of the loop taker after startingof a sewing operation, and to cause said lever to cam with and to hesubsequently retracted into said groove by said first re- 3,1 3 silientmeans upon approaching its locked position with said disk, as willbecome further apparent from the following detailed description of thedrawing.

Referring more particularly to FIG. 1, the numeral 1 denotes the workingtable or bed plate of a conventional sewing machine upon which ismounted a housing 2 comprised in a known manner of an upright and anoverhanging arm being parallel to said plate and terminating in a sewinghead 3. Mounted within the head 3 is a reciprooable needle bar 4carrying a needle 5 at its lower end. A main drive shaft 6 beingjournalled in the overhanging arm of the housing 2 serves to operate theneedle bar 4 through a conventional crank and link connection (notshown) and carries a flywheel 7 at its opposite end, said shaft beingdriven in a known manner by a motor (not shown) through a suitablestarting or control device for the carrying out of a sewing operation.

Iournalled below the bed 1 is a loop taker drive shaft 8 which carries asprocket wheel or the like 9, said shaft being driven, in the exampleshown, by means of a chain belt 11 cooperating with the wheel 9, on theone hand, and with a further sprocket or drive wheel mounted upon thearm shaft 6, on the other hand.

Further journalled below the bed 1 at a distance from and panallel tothe first loop taker shaft 8 is a second drive shaft 12, said shaftsbeing coupled with one another through a pair of gears 13 and 14,whereby to rotate both shaft 3 and 12 at the same speed.

Secured to the front end of the first loop taker drive shaft 8 is aneccentric 15 being encircled by the upper annular-shaped part 16 of aneccentric rod 17. The lower part 18 of said rod is in turn linked, bymeans of a pin 19, at its upper fork-shaped end to the part 16, whilethe lower end of part 18 forms the socket or hearing of a ball jointwhich further comprises the spherical-shaped end 26 of a lever arm orlink 21 secured to a loop taker casing or carrier 22. Extendinglaterally from the carrier 22 is a further arm 23, which is journalled,by means of a pin or shaft 24, in a fork-shaped hearing or adjustablesupport 25 of the loop taker casing or carrier 22. For this purpose, thesupport 25 has a shaft 26 extending therefrom at right angle to the pin24 and being rotatably mounted in the bed 1 or frame of the sewingmachine.

Secured to the shaft 26 is one end of a further link or arm 27 theopposite end of which is in turn linked, by means of a pin 28, to thelower end of a further eccentric rod 29 having its opposite endencircling an eccentric 31) mounted upon the end of the second looptaker drive shaft 12. The two eccentric drives 1524 and 26-30 connectingthe loop taker carrier 22 with the shafts 8 and loop taker 32 must bethreaded by the needle: and loop taker threads, respectively, in amanner well known in the operation of chainstitch sewing machines.

In the example shown, the loop taker support 31 has a depending shaft 31journalled in the carrier 22, said support having secured thereto thethread carrying hook or loop taker 32 of usual construction. The support31 is secured axially by the provision of a separating sleeve 33intermediate said support and said carrier and surrounding the shaft 31,on one hand, and by a cam or locking disk 34 secured to the lower end ofsaid shaft, on the other hand. Fulcrumed in a fork-shaped lateralextension 35 of the casing or carrier 22, by means of a pin 37, is adouble locking and release lever 36 which has an angular extension orarm 38 subject to the action of a relatively strong coil spring 40 orthe like engaging said arm, on the one hand, and engaging a projection39 of the casing 22, on the other hand, in the manner shown in thedrawing. The ring 34 has a groove 41 adapted to receive the lockinglever 36 in the retracted or operative position of the loop taker. Oneedge of the groove 41 is formed control mechanism describedhereinbefore.

4;. with a bevelled or cam-shaped surface 4 FIG. 4, the purpose of whichwill become apparent as the description proceeds.

Surrounding the sleeve 33 is a further coil spring 43 having one endfixedly engaging the carrier 22 and having its opposite end fixed, inthe example shown, to the loop taker support 31, in such a manner as tostress or tension said spring in the normal or locked position of thelever 36 or loop taker 32, as shown in FIG. 2. As a consequence,unlocking of the disk 34 by depressing the lever arm 38 will result in arelative rotation of the support 31 and loop taker 32 from an operativeto a threading position by the action of the spring 43, as shown in fulllines in FIG. 3 and will be further explained in the following.

Further secured to the bed 1, by means of a set screw 4'7, is a stop andcam plate 45, FIG. 3, being shaped at its end facing the loop taker 32or support 31 in the form of a curve or cam 48 consisting of twosections 49 and 53 meeting at a common apex S which is positioned at apredetermined distance from the elliptical loop taker operating path 51,as shown in the drawing. Both curves 49 and 5b of the cam 48 are shapedand arranged relative to the loop taker 32 or its operating path 51 suchas to result in an automatic return of the loop taker from its threadingposition, shown in full lines in FIG. 3, to its operative position,shown in dot-dash lines by cooperation with the disk 34 and lockinglever 36 during the starting of a sewing operation, as will becomefurther apparent from the following description of the operation of theloop taker Adjustment of the plate 45 is effected by means of the setscrew 47 passing through slot 46.

The preparation of a chainstitch sewing machine prior to the beginningof a sewing operation includes, among other adjustments and controls,the threading of the chainstitch loop taker or hook 32. In its normal oroperative position, the loop taker, in most practical cases is eitherinaccessible or accessible with difficulty only, since the hook oreye-opening of the loop taker is normally underneath and concealed bythe bed 1 or stitching plate of the machine (not shown). To enablethreading, the housing or carrier 22 together with the loop taker are atfirst operated by continued rotation of the sewing machine to a positioncorresponding to the end of the return stroke or beginning of theforward stroke within the elliptical loop taker path 51 or operatingcycle, as shown in FIG. 3.

Subsequent actuation of the locking lever 36 by digital pressure uponthe arm 38 against the action of the spring 40 will result in adeflection of said lever and disengagement from the groove 41 of thedisk 34, thereby allowing the spring 43, being normally under stress ortension, to rotate the loop taker support 31 and with it the loop taker32 relative to the carrier 22 to its threading position, in the mannerpointed out hereinbefore and illustrated, in full lines in FIG. 3, thecam plate 45 during this operation forming a stop or abutment for theloop taker in the threading position.

After the loop taker has been properly threaded, the machine may bestarted for the commencement of a sewing operation, whereby to operatethe carrier 22 through 'the eccentric drives 15-24 and 26-30 in thecoordinate directions and to result in the loop taker being displacedalong its elliptical operating path 51 from the starting point shown inthe drawing.

As a consequence, the loop taker 32 or its support 31 by engaging thesection 49 of the cam 38 causes the support 31 and with it the shaft 31'and disk 34 to be rotated relative to the carrier 22 until the cam orbevelled surface 44 of the disk 34 engages or cams with the surface 42of the locking lever 36 sliding upon the periphery of said disk, tothereby result in the retraction of said lever into the groove 41 andlocking of the loop taker in its operative position by the action of thespring 411. Return of the loop taker to and locking in its operativeposition is fully automatic by the cooperation of surfaces 44 and 49and, in response to the normal starting of the sewing machine for thecommencement of a sewing operation. The prior difiiculties and drawbacksare accordingly substantially eliminated by the adjusting and controlmechanism of the present invention.

Section 50 of the cam 48 is provided for the sake of safety in case theloop taker threading is carried out inadvertently and the sewing machinestarted in the opposite loop taker position, that is, at the end of itsforward stroke or the beginning of the return stroke within theoperating path 51. Again, section 50 by engaging the intermediate arm ofthe loop taker 32 serves as a stop limiting the deflection of the looptaker to the threading position. As seen from FIG. 3, the long axis ofthe ellipse 51 includes an angle with the lengthwise axis of the plate45. During the return stroke of the loop taker 32, the intermediate armcamming with the section 50 again will effect the retraction to theoperative position in conjunction with the cam surface 44, insubstantially the same manner as described hereinbefore.

In the foregoing the invention has been described with reference to aspecific illustrative device. It will be evident, however, thatvariations and modifications, as well as the substitution of equivalentelements or parts for those shown herein for illustration, may be madeWithout departing from the broader purview and spirit of the inventionas set forth in the appended claims. The specification and drawing areaccordingly to be regarded in an illustrative rather than in arestrictive sense.

Having thus described the invention, I claim:

1. In a chainstitch sewing machine of the type having a reciprocatoryneedle, a thread-carrying loop taker, a carrier therefor and means tooperate the same over an elliptical operating path in synchronism withsaid needle, to sew double chainstitches in a work piece being operatedon; the improvement comprising means to rotatively support said looptaker by said carrier for operation between a sewing and a threadingposition, releasable locking means including first resilient means tolock said loop taker in the sewing position with said carrier, secondresilient means connecting said loop taker with said carrier and adaptedin the stressed condition and locked position of said loop taker torotate the same, said loop taker being positioned at a predeterminedpoint of said operating path prior to a sewing operation and beingrotated in a first direction from its sewing to its threading positionupon release of said locking means and against the action of said firstresilient means, and stationary cam means forming a stop for said looptaker in said threading position and adapted to cam with said loop takerduring the initial loop taker displacement by said carrier upon startingof a sewing operation, whereby to initiate the return of the loop takerto the sewing position by rotating the same in the direction opposite tosaid first direction and against the action of said second resilientmeans to a position for completion of its return to the locked positionby the action of said first resilient means.

2. In loop taker adjusting mechanism as claimed in claim 1, said firstmeans being comprised of a shaft extending from said loop taker andjournalled in said carrier, and said locking means being comprised of adisk carried by said shaft and having a peripheral groove, and anoperating lever fulcrumed upon said carrier and having an arm urged intopeipheral engagement with said disk by the action of said firstresilient means and engaging said groove in the locked position of saidloop taker.

3. In loop taker adjusting mechanism as claimed in claim 2, said leverhaving a second arm, and said first resilient means consisting of a coilspring connecting said last arm with said carrier.

4. In loop taker adjusting mechanism as claimed in claim 2, said secondresilient means consisting of a coil spring surrounding said shaft andhaving its opposite ends fixedly engaging said loop taker and carrier,respectively.

5. In loop taker adjusting mechanism as claimed in claim 2, said groovehaving a curved edge adapted to cam with said arm upon said groovereaching a predetermined position from said arm during the returnmovement of said loop taker.

6. In a chainstitch sewing machine of the type having a bed plate, areciprocatory needle carrying a needle thread and mounted above saidplate, a loop taker having an eyepointed hook carrying a looper threadand mounted below said plate, a carrier for said loop taker and means tooperate the same over an elliptical operating path in synchronism withsaid needle, to sew double chain stitches in a work piece fed along saidplate, said loop taker hook occupying a normally inaccessible operativeposition throughout said operating path; the improvement comprisingmeans to rotatively support said loop taker by said carrier foroperation between a sewing and a threading position, releasable lockingmeans including first resilient means to lock said loop taker in thesewing position with said carrier during the carrying out of a sewingoperation, second resilient means connecting said loop taker with saidcarrier and adapted in the stressed and locked position of said looptaker to rotate the same, said loop taker being positioned at apredetermined point of said operating path prior to the commencement ofa sewing operation and being rotated in one direction from said sewingposition to said threading position upon release of said locking meansand against the action of said first resilient means, and stationary cammeans forming a stop for said loop taker in the threading position andadapted to cam with said loop taker during the initial displacement ofsaid loop taker by said carrier upon starting of a sewing operation,whereby to initiate the return of the loop taker to the sewing positionby rotating the same relative to said carrier in the direction oppositeto said first direction and against the action of said second resilientmeans to a position for completion of its return to the locked positionby the action of said first resilient means.

7. In loop taker adjusting mechanism as claimed in claim 6, said cammeans being positioned for cooperation with said loop taker in thestarting position of its operating path.

8. In loop taker adjusting mechanism as claimed in claim 6, said firstmeans being comprised of a shaft extending from said loop taker andjournalled in said carrier, and said locking means being comprised of adisk secured to the end of said shaft and having a peripheral groove,and a double lever fulcrumed upon said carrier and having an operatingarm connected to said carrier through a coil spring constituting saidfirst resilient means, and a second lever arm resiliently bearing uponthe periphery of said disk and engaging said groove in the lockedposition of said loop taker.

9. In loop taker adjusting mechanism as claimed in claim 8, said groovehaving a curved edge adapted to cam with said second lever arm upon saidgroove reaching a predetermined distance from said arm during the returnmovement of said loop taker.

10. In loop taker adjusting mechanism as claimed in claim 7, said secondresilient means consisting of a coil spring surrounding said shaftintermediate said loop taker and said carrier and having its oppositeends fixedly engaging said loop taker and carrier, respectively.

11. In a chainstitch sewing machine of the type having a reciprocatoryneedle, a thread-carrying loop taker, a carrier therefor and means tooperate the same over an elliptical operating path in synchronism withsaid needle, to sew double chain stitches in a work piece being operatedon; the improvement consisting in the provision of adjusting mechanismto operate said loop taker between a normally inaccessible operativeposition and an accessible threading position comprising means torotatively support said loop taker by said carrier, spring-urgedmanually releasable locking means to normally maintain said loop takerin its operative locked position with said carrier,

resilient means connecting said loop taker with said carrier and adaptedin the stressed condition and operative loop taker position, to rotatesaid loop taker from its operative position to its threading positionupon release of said locking means, and stationary cam means arranged tobe engaged by said loop taker in the threading position and adapted tocam therewith upon displacement of said loop taker by said carrier afterstarting of a sewing operation, whereby to initiate the return of saidloop taker to References Cited in the file of this patent UNITED STATESPATENTS Zeier et a1. June 6, 1933 Irmscher July 7, 1959 Hacklander July26, 1960

1. IN A CHAINSTITCH SEWING MACHINE OF THE TYPE HAVING A RECIPROCATORYNEEDLE, A THREAD-CARRYING LOOP TAKER, A CARRIER THEREFOR AND MEANS TOOPERATE THE SAME OVER AN ELLIPTICAL OPERATING PATH IN SYNCHRONISM WITHSAID NEEDLE, TO SEW DOUBLE CHAINSTITCHES IN A WORK PIECE BEING OPERATEDON; THE IMPROVEMENT COMPRISING MEANS TO ROTATIVELY SUPPORT SAID LOOPTAKER BY SAID CARRIER FOR OPERATION BETWEEN A SEWING AND A THREADINGPOSITION, RELEASABLE LOCKING MEANS INCLUDING FIRST RESILIENT MEANS TOLOCK SAID LOOP TAKER IN THE SEWING POSITION WITH SAID CARRIER, SECONDRESILIENT MEANS CONNECTING SAID LOOP TAKER WITH SAID CARRIER AND ADAPTEDIN THE STRESSED CONDITION AND LOCKED POSITION OF SAID LOOP TAKER TOROTATE THE SAME, SAID LOOP TAKER BEING POSITIONED AT A PREDETERMINEDPOINT OF SAID OPERATING PATH PRIOR TO A SEWING OPERATION AND BEINGROTATED IN A FIRST DIRECTION FROM ITS SEWING TO ITS THREADING POSITIONUPON RELEASE OF SAID LOCKING MEANS AND AGAINST THE ACTION OF SAID FIRSTRESILIENT MEANS, AND STATIONARY CAM MEANS FORMING A STOP FOR SAID LOOPTAKER IN SAID THREADING POSITION AND ADAPTED TO CAM WITH SAID LOOP TAKERDURING THE INITIAL LOOP TAKER DISPLACEMENT BY SAID CARRIER UPON STARTINGOF A SEWING OPERATION, WHEREBY TO INITIATE THE RETURN OF THE LOOP TAKERTO THE SEWING POSITION BY ROTATING THE SAME IN THE DIRECTION OPPOSITE TOSAID FIRST DIRECTION AND AGAINST THE ACTION OF SAID SECOND RESILIENTMEANS TO A POSITION FOR COMPLETION OF ITS RETURN TO THE LOCKED POSITIONBY THE ACTION OF SAID FIRST RESILIENT MEANS.